1. Field of Invention
The present invention relates to a fan and a fan assembly, and in particular to a fan having the improved arrangement of a circuit board, and a fan assembly.
2. Related Art
With the enhancements of functions and operating speeds of electronic products, heat generated is correspondingly increased during the operation of the electronic products. In order to keep the normal operation of the electronic products, a fan is provided to dissipate heat in the prior art.
Because the efficiency and the miniaturized requirement of the modern electronic product are increased, the heat dissipating requirement is correspondingly increased. In view of this, it is an important subject to increase the efficiency of the fan in this industry. In the prior art, the efficiency of the fan is increased by reducing the size of the impeller or increasing the rotating speed of the fan. However, such a design accompanies the larger current for driving the motor to rotate. In other words, more electronic components or a larger electronic component is needed to drive the motor to rotate. As the results, the space for the circuit board 123 becomes insufficient. Referring to FIG. 1, which is a schematic illustration showing a structure of a conventional fan 1. In FIG. 1, the impeller 11, the motor 12, and the circuit board 123 are accommodated in the fan frame 13. In order to enlarge the space for containing more electronic components on the circuit board, a projecting lug 123a is designed at the outer periphery of the circuit board 123. However, because the lug 123a is non-symmetrically disposed on the circuit board 123 and extends outwardly from the periphery to the circuit board 123, the flowing directions and the flows of the air streams are influenced by the lug 123a and thus the turbulence or vortex phenomenon are generated. As the results, the efficiency of the fan 1 is decreased and noises are generated. Such results become more apparent in the small-sized fan.